Abstract
In this work,the mechanical properties and strengthening mechanisms induced by microstructural evolu-tion in a rheo-extruded 5087 alloy processed via accumulative continuous extrusion forming(ACEF)were investigated.Electron back-scattered diffraction(EBSD)and transmission electron microscopy(TEM)were utilized to characterize the microstructure of the alloy subjected to ACEF with various passes.The grain refinement caused by continuous dynamic recrystallization(CDRX)was discussed.The results demon-strated that after 3 passes of ACEF,there was a significant grain refinement effect on the alloy,and the average grain size decreased from 45.6 μm to 2.5 μm;the ultimate tensile strength(UTS)and yield strength(YS)of the alloy increased to 362.8 MPa and 234.6 MPa,respectively.Dislocation cells/walls gen-erated during deformation promoted the formation of low angle grain boundaries(LAGBs).The accumu-lative strain accelerated the transformation of LAGBs to high angle grain boundaries(HAGBs).Dislocation pile-up enhanced the driving force of CDRX,and nano-sized Al6(Mn,Fe)phases at the grain boundaries inhibited the growth of grains due to the pinning effect.Based on the quantitative estimation,dislocation strengthening and grain boundary strengthening dominated the enhancement in YS of the ACEFed alloy.
基金项目
国家重点研发计划(2018YFB2001800)
国家自然科学基金(51871184)
Dalian High-level Talents Innovation Support Program(2021RD06)
Dongguan Graduate Workstation Project(20201900300032)
NETL
NSTL
万方数据